#include <thrust/sort.h>

#include <cuda/std/utility>

#include <unittest/unittest.h>

struct make_pair_functor
{
  template <typename T1, typename T2>
  _CCCL_HOST_DEVICE cuda::std::pair<T1, T2> operator()(const T1& x, const T2& y)
  {
    return cuda::std::make_pair(x, y);
  } // end operator()()
}; // end make_pair_functor

template <typename T>
struct TestPairStableSort
{
  void operator()(const size_t n)
  {
    using P = cuda::std::pair<T, T>;

    thrust::host_vector<T> h_p1 = unittest::random_integers<T>(n);
    thrust::host_vector<T> h_p2 = unittest::random_integers<T>(n);
    thrust::host_vector<P> h_pairs(n);

    // zip up pairs on the host
    thrust::transform(h_p1.begin(), h_p1.end(), h_p2.begin(), h_pairs.begin(), make_pair_functor());

    thrust::device_vector<P> d_pairs = h_pairs;

    // sort on the host
    thrust::stable_sort(h_pairs.begin(), h_pairs.end());

    // sort on the device
    thrust::stable_sort(d_pairs.begin(), d_pairs.end());

    ASSERT_EQUAL_QUIET(h_pairs, d_pairs);
  }
};
VariableUnitTest<TestPairStableSort, unittest::type_list<unittest::int8_t, unittest::int16_t, unittest::int32_t>>
  TestPairStableSortInstance;
